A time bound on the materialization of some recursively defined views

A virtual relation (or view) can be defined with a recursive Horn clause that is a function of one or more base relations. In general, the number of times such a Horn clause must be applied in order to retrieve all the tuples in the virtual relation depends on the contents of the base relations of the definition. However, there exist Horn clauses for which there is an upper bound on the number of applications necessary to form the virtual relation, independent of the contents of the base relations. Considering a restricted class of recursive Horn clauses, we give necessary and sufficient conditions for members of the class to have this bound.     

A note on the recursive enumerability of some classes of recursively enumerable languages

An elementary proof is presented for the fact that the class of infinite recursive languages is not recursively enumerable. Its relevance for contemporary linguistics and computer science is explained.     

A computational method of forecasting based on fuzzy time series

In this paper, a computational method of forecasting based on fuzzy time series have been developed to provide improved forecasting results to cope up the situation containing higher uncertainty due to large fluctuations in consecutive year's values in the time series data and having no visualization of trend or periodicity. The proposed model is of order three and uses a time variant difference parameter on current state to forecast the next state. The developed model has been tested on the historical student enrollments, University of Alabama to have comparison with the existing methods and has been implemented for forecasting of a crop production system of lahi crop, containing higher uncertainty. The suitability of the developed model has been examined in comparison with the other models to show its superiority.     

A survey on the use of pattern recognition methods for abstraction, indexing and retrieval of images and video

The need for content-based access to image and video information from media archives has captured the attention of researchers in recent years. Research efforts have led to the development of methods that provide access to image and video data. These methods have their roots in pattern recognition. The methods are used to determine the similarity in the visual information content extracted from low level features. These features are then clustered for generation of database indices. This paper presents a comprehensive survey on the use of these pattern recognition methods which enable image and video retrieval by content.     

A fuzzy analysis of country-size argument for the Feldstein-Horioka puzzle

This study aims to analyze the effect of country size, represented by relative Gross National Products (GNP), on the association between domestic investment and saving, using data from a panel of 21 OECD countries. The countries are clustered into four groups with respect to their relative country sizes with an application of Fuzzy c-Means clustering technique. The novelty of this approach is that it is an unsupervised method that generates membership values between zero and one instead of binary values that take values of zero or one only. In addition to this it has the advantages of its tolerance to imprecise data and the ease of understanding. The results show that the saving retention coefficients are greater for larger countries except for the cluster which contains the largest country. Thus, this work presents only partial evidence that the country size affects the relationship of domestic saving and investment.     

A branch and bound algorithm for minimizing total completion time on a single batch machine with incompatible job families and dynamic arrivals

In this paper, we consider a single batch machine scheduling problem with incompatible job families and dynamic job arrivals. The objective is to minimize the total completion time. This problem is known to be strongly NP-hard. We present several dominance properties and two types of lower bounds, which are incorporated to construct a basic branch and bound algorithm. Furthermore, according to the characteristics of dynamic job arrivals, a decomposed branch and bound algorithm is proposed to improve the efficiency. The proposed algorithms are tested on a large set of randomly generated problem instances.     

A Reasoning Model Based on the Production of Acceptable Arguments

Argumentation is a reasoning model based on the construction of arguments and counter-arguments (or defeaters) followed by the selection of the most acceptable of them. In this paper, we refine the argumentation framework proposed by Dung by taking into account preference relations between arguments in order to integrate two complementary points of view on the concept of acceptability: acceptability based on the existence of direct counter-arguments and acceptability based on the existence of defenders. An argument is thus acceptable if it is preferred to its direct defeaters or if it is defended against its defeaters. This also refines previous works by Prakken and Sartor, by associating with each argument a notion of strength, while these authors embed preferences in the definition of the defeat relation. We propose a revised proof theory in terms of AND/OR trees, verifying if a given argument is acceptable, which better reflects the dialectical form of argumentation.     

A bound on the projective dimension of three cubics

We show that given any polynomial ring R over a field and any ideal JR which is generated by three cubic forms, the projective dimension of R/J is at most 36. We also settle the question of whether ideals generated by three cubic forms can have projective dimension greater than 4, by constructing one with projective dimension equal to 5.     

A lower bound on the area of permutation layouts

In this paper we prove a tight (n ³) lower bound on the area of rectilinear grids which allow a permutation layout ofn inputs andn outputs. Previously, the best lower bound for the area of permutation layouts with arbitrary placement of the inputs and outputs was (n ²), though Cutler and Shiloach [CS] proved an (n ^2.5) lower bound for permutation layouts in which the set of inputs and the set of outputs each lie on horizontal lines. Our lower bound also holds for permutation layouts in multilayer grids as long as a fixed fraction of the paths do not change layers.The first author's research was partially supported by NSF Grant No. MCS 820-5167. The third author's research was supported by NSF Grant No. MCS-8204246 and by a Hebrew University Fellowship.     

A lower bound on the integral of the nonlinear filtering error

A lower bound on the nonlinear filtering error derived on the basis of information theoretic considerations will be proposed. The tightness of this bound will be shown in an example.     

A lower bound on the period length of a distributed scheduler

Ad-scheduling of a graphG is a sequence of rounds, each consisting of some of the nodes of the graph, such that the distance between any two nodes participating in the same round is greater thand. Ad-scheduler is a protocol that determines ad-scheduling ofG. A 1-scheduler is applicable to process scheduling in a resource-sharing system, and to proper communication scheduling of the half-duplex model in communication networks. A 2-scheduler can be used as a collision-free protocol for radio networks.In this paper a simpled-scheduler is analyzed. We first discuss basic properties of this scheduling, and give a complete characterization of this scheduling for trees and cycles. We study the period length of this scheduling, and the main result is a worst-case exponential lower bound for this length.The research of Shmuel Zaks was supported by the Fund for Research in Electronics, Computers, and Communications adminstered by the Israeli Academy of Sciences and Humanities.     

A lower bound on the mod 6 degree of the OR function

We examine the computational power of modular counting, where the modulus m is not a prime power, in the setting of polynomials in Boolean variables over Z _m . In particular, we say that a polynomial P weakly represents a Boolean function f (both have n variables) if for any inputs x and y in {0,1}ⁿ, we have whenever . Barrington et al. (1994) investigated the minimal degree of a polynomial representing the OR function in this way, proving an upper bound of O(n ^{1/ r} ) (where r is the number of distinct primes dividing m) and a lower bound of . Here, we show a lower bound of when m is a product of two primes and in general. While many lower bounds are known for a much stronger form of representation of a function by a polynomial (Barrington et al. 1994, Tsai 1996), very little is known using this liberal (and, we argue, more natural) definition. While the degree is known to be for the generalized inner product because of its high communication complexity (Grolmusz 1995), our bound is the best known for any function of low communication complexity and any modulus not a prime power. received 29 September 1994     

A note on the lower bound of edge guards of polyhedral terrains

Bose et al. [P. Bose et al., Guarding polyhedral terrains, Comput. Geom., Theory Appl. 6 (1997), pp. 173–185.] proved that ? (4n?4)/13 ? edge guards are sometimes necessary to guard an n-vertex polyhedral terrain. Subsequently, Kau?i? et al. [B. Kau?i?, B. ?alik, and F. Novak, On the lower bound of edge guards of polyhedral terrains, Int. J. Comput. Math. 80 (2003), pp. 811–814.] claimed to find an inconsistency in the proof and used Bose et al. ’s proof technique to prove a weaker lower bound of ? (2n?4)/7 ? edge-guards. They declared that a proof of the original lower bound of ? (4n?4)/13 ? remains an open issue. The purpose of this note is simply to point out that the issue is not open and that Bose et al. ’s original proof is correct. We present the original proof of ? (4n?4)/13 ? at a level of detail to hopefully remove any misunderstanding of the result.     

A simple algorithm for testing the stability of periodic solutions of some nonlinear oscillators with large time delay

Periodic solutions occur commonly in linear or nonlinear dynamical systems. In some cases, the stability of a periodic solution holds if the rightmost characteristic root has negative real part. Based on the Lambert W function, this paper presents a simple algorithm for locating the rightmost characteristic root of periodic solutions of some nonlinear oscillators with large time delay. As application, the proposed algorithm is used to study the primary resonance and 1/3 subharmonic resonance of the Duffing ...     

A large lower bound on the query complexity of a simple boolean function

Combinatorial property testing, initiated formally by Goldreich, Goldwasser, and Ron (1998) and inspired by Rubinfeld and Sudan (1996), deals with the relaxation of decision problems. Given a property P the aim is to decide whether a given input satisfies the property P or is far from having the property. For a family of boolean functions f=(fn) the associated property is the set of 1-inputs of f. Here, the known lower bounds on the query complexity of properties identified by boolean functions representable by (very) restricted branching programs of small size is improved up to Ω(n1/2), where n is the input length.     

A bound on the number of integrators needed to linearize a control system

This paper considers the problem of dynamic feedback linearization for nonlinear control systems. For a restricted class of dynamic compensators that correspond to adding chains of integrators to the inputs, we give an upper bound on the order of the compensator that needs to be considered. In the case of 2-input systems, we show that this bound is sharp.     

The main features of BAHUS — biometeorological system for messages on the occurrence of diseases in fruits and vines

Recently, there has been an increasing demand for providing a high level of production of wholesome plant food but without losing its quality from the consumer's point of view. In this regard, it is required to provide reliable information about the occurrence of plant diseases so as to ensure their efficient control. The reliability of this information increases substantially if both the meteorological and the biological quantities, measured or modelled, are properly integrated in a prognostic system. By the joint efforts of the authors' institutions the biometeorological system BAHUS for messages on the occurrence of the most important diseases in fruits and vines has been developed. This system has been developed in Microsoft FoxPro 2.6(X) following standards of analysis of a large amount of data. It consists of two modules. The first provides input for prediction in the form of the measured or modelled meteorological and biological data, while the second, on the basis of available input data, selects the corresponding method for messages on the occurrence of disease. Depending on the method selected, the meteorological data can be assimilated either from weather stations, atmospheric models or software packages LAPS (land–air parameterization schemes providing 10 min prognostic values) and KARLOS (providing their climatological values) integrated in the system as a whole. The BAHUS has been designed as an open system giving a wide range of possibilities for increasing its level of sophistication.     

A note on the coprime fractional representation of nonlinear feedback systems

A very large infinite-dimensional Banach space of bounded nonlinear operators is suggested as an underlying framework for studies of nonlinear systems control. Meanwhile, it is pointed out that all results obtained in Verma [6] can be extended to this much larger family of nonlinear control systems.